The research by business information providers Experian found the financial services sector reduced the time taken to pay its bills by 3.11 days, to an average period of 58.44 days.

And medium-sized companies in the sector were fastest payers across the entire economy, taking just 49 days to settle their debts. The next best were medium-sized alcoholic beverage manufacturers who took 51 days and medium-sized insurance companies which took 52 days.

But the overall trend across the UK saw average payment periods increase as economic conditions worsen. This despite the introduction of legislation in 1999 which gave small companies the right to interest on late payments.

Companies are now taking almost a day more, 60.34 days, from the time they receive invoices to the time they pay them. Last November companies took 59.63 days to pay their bills.

He added: ‘Their priorities are to maintain cash flow and protect the jobs of their employees. The result is that payment times are even longer than when the legislation was introduced.’

The worst offenders were medium-sized companies, with 21 out of 29 sectors increasing the payment period, some by as much as 20 days, while large companies on average took an extra 1.5 days to pay up.

The oil industry was the slowest paying sector, taking on average more than a week longer to settle bills, despite oil giants such as BP reporting profits of more than Pounds 1m an hour.

Gas and oil companies of all sizes took substantially longer to pay bills with small companies taking on average of a week longer, medium-sized companies taking between two and three weeks longer pushing the payment period to 86 days, or almost three months.

Small companies were the most prompt payers, taking less time than the industry average at 58.6 days – 0.3 days less than nine months ago. Sixteen of the 29 small company sectors took longer to pay their bills.

Experian said it had expected to see an improvement in payment times to small companies, but found little evidence that companies were willing to exercise their rights against their customers.

Kilmister said late payment was not just an ‘indication of possible cash flow problems’, but was also an ‘attitude whereby some people believe it is acceptable to withhold payment of invoices until long after the agreed contractual period’.